Portable knife sharpener



1959 J. A. HERMANN ET AL 2,897,640

PORTABLE KNIFE SHARFENEIR I Filed Aug. 3, 1956 2 Sheets-Sheet l FIG. 1

l 42 I0 I I l I:

2'7 28 I3 47/ E a INVENTOR. Joseph H. Hermann Raymond W. Lorence, Sr. BY

rs E v I Attorney Aug. 4, 1959 J. A. HERMANN ET AL PbRTABLE KNIFE SHARPENER 2 Sheets-Sheet 2 Filed Aug. 5, 1956 INVENTOR. Joseph A. Her agmowd YY- ko ren BY United States Patent PORTABLE KNIFE SHARPENER Joseph A. Hermann and Raymond W. Lorence, Sr.-, Akron, Ohio Application August 3, 1956, Serial No. 601,912

4 Claims. (Cl. 51--173) This invention relates to a knife sharpener, and in particular relates to a portable unit for sharpening the beveled cutting edge of a paper cutting blade.

One object of the invention is to provide a portable sharpening unit of the character described, wherein means is provided for progressively sharpening the blade in a manner which assures a uniformly straight, sharp edge.

Another object of the invention is to provide a sharpening unit having improved means for adjusting the cutting position of abrasive means thereof, to control the desired shape of the cutting edge on the work.

Another object of the invention is to provide an improved sharpening unit wherein progressive cutting is ening unit, embodying the features of the invention.

Figure 2 is a front elevation thereof, but illustrating the unit mounted on a paper cutting blade, for a late stage of cutting action on the work, the cutting blade being shown partly broken away and in cross-section.

Figure 3 is an end view of the unit, as viewed from the right of Figure 1.

Figure 4 is a vertical cross-section, taken substantially on the line 4-4 of Figure 3, and illustrating parts of the unit in position for an earlier stage of cutting action on the work.

Referring to the drawings generally, there is illustrated a portable blade sharpening unit 10, wherein a holder 11 includes a backing plate 12 at an inner side of which spaced lugs 13 and 14 are afiixed to extend at right angles to the plane of a flat inner surface 15 of the backing plate. Cut-outs 16 in the lugs, adjacent backing plate 12 permit upward insertion of a fixedly supported cutter blade 17, as limited by a bar 18 secured across the bottom edges of the lugs. When the holder is gravitationally supported on the cutter blade, as best shown in Figures 2 and 4, the flat inner surface 15 of the backing plate fits flatly against the outer face 19 of the blade, and a chamfered edge 20 of guide bar 18 engages the lowermost portion of the beveled face 22 of the blade. Thus the bar 18 and the inner surface portion 15 of plate 12 serve as guide means for properly positioning the holder on the blade.

Pivoted to opposite inner sides of the lugs 13 and 14 may be a pair of spaced elongated bars 23 and 24, respectively, of a pivotally adjustable U-shaped member 25, the outer ends of the bars 23 and 24 being rigidly held apart by a spacer 26 suitably secured between the same. For pivotally affixing the member in various angularly adjusted positions with reference to holder 11, an arm 27 may be adjustably afiixed to the holder lug '13 to extend in the same general direction as member 25,

"2,897,640 Patented Aug. 4, 1959.

i e j and manually operable adjusting means 28 is provided between the fixed arm 27 and bar 23. The adjusting means 28 may comprise a cam disc 30 pivoted on arm 27, and having an eccentric pin 32 received through an elongated cam slot 33 in said bar 23. A knob 34 affixed to a reduced extension 35 of cam disc 30, rotatably retains the disc on arm 27, and is operable to turn the disc between the relative positions thereof shown in Figures 2 and 4, by which eccentric movement of pin 32 in slot 33 is effective to pivot member 25 about the pivotal connections 36 thereof to the holder lugs 13 and 14. The arrangement is such that the cam disc 28 will stay in any given position of rotation thereof to fix the member 25 in a corresponding fixed angular position thereof with respect to arm 27 and holder 11. For visibly indicating various said angular positions, suitable indicia, such as marks 37 and 38 may be provided on the periphery of the disc and the upper edge of bar 23, respectively.

Pivoted between the bars 23 and 24, at the outer end of the member 25, and at a substantial distance from holder 11, may be an elongated element 39, on the inner or opposite end of which is removably attached an abrasive stone 40, which is shown as being circular and having a convex beveled edge 41. The arrangement is such that in various positions of pivoted angular adjustment of element 39, the lowermost portion of the beveled edge 41 of the stone is presented to be in contact with the beveled edge 22 of the blade 17 at various points, two of which points are shown in Figures 2 and 4. The general radius from the beveled surface portion of the stone to the pivot 42 is relatively great, and proportioned so that angular adjustments of the element 39 may be made progressively to swing the lower bevelededge portion of the stone in a definite are which will cut a uniformly smooth and straight, hollow ground face in the blade 17, in a manner to be described later.

For yieldingly urging the stone 40 downwardly against the beveled edge of blade 17, a leaf spring 43, attached to the element 39, has a free extension 44 in constant yielding engagement with the spacer 26.

Handles 45 and 46 may be provided on the upper side of element 39 and the outer side of holder plate 12, respectively. By gripping one of these handles in each hand an operator may reciprocate the sharpening unit longitudinally of the blade 17.

A wider range of relative angular adjustment of the member 25 and element 39 may be accomplished, as by pivoting the arm 27 to lug 13 at 46 and locking the arm to said lug 13 in various positions of pivoted angular adjustment of the arm, as by means of a locking screw 47 received through an arcuate slot 48 in an extension 49 of the arm, and threaded into the lug 13.

In operation of the improved unit 10, as for sharpening an elongated paper cutting blade 17, the operator first fixedly mounts the blade in a suitable fixed support S, as shown in Figure 2, and then mounts the unit on the blade to have the beveled edge portion thereof received in the cut-out portions 16 of the lugs, with the fiat outer side 19 of the blade backed against the inner guide surface 15 of the backing plate 12 of the holder 11, and the chamfered edge 20 of guide bar 18 engaging the lower portion of the bevel 20 of the blade.

Next, the operator, after affixing the arm 27 on the holder 11, by means of locking screw 47, operates the cam means 28 to adjust the angle of member 25 with respect to said. fixed arm 27, to present the, lowermost beveled edge portion of the stone 40 against the top edge of the blade, substantially as shown in Figure 4. In this position, in which the stone is uniformly yieldingly urged against the blade, the operator, by means of the handles 45 and 46, reciprocates the unit longitudinally of the r a 3, blade and thereby sharpens a narrow strip along said tip edge of the blade.

By progressively adjusting the stone in a downward are, between the positions shown in Figures 2 and 4,

through adjustment of the cam means 28, as indicated by 5 the indicia '37 and 38, the reciprocatingmovement may be repeated until the blade edge is suitably hollow ground with a straight sharp edge, as shown in Figure 2. l

Thus has been provided a simple sharpening unit which is easy to adjust upon and to remove from the work, and which may be operated with a minimum of skill to obtain a uniformly smooth, sharp cutting edge on a blade of the type described.

While the circular abrasive stone 40 is non-rotatably.

affixed 'on the end of element 39, it is contemplated that l. A device for sharpening a cutter blade having an elongated beveled cutting edge portion, comprising a rigid holder having fixedly spaced longitudinally extending guide portions for downwardly engaging opposing sides of the beveled edge portion of the blade, whereby the holder is adapted to be firmly but longitudinally slidably selfsupported directly on said cutting edge portion while the 4 blade is held aflixed in a vertical plane with said edge portion presented upwardly, a rigid member rigidly atfixed to said holder to extend freely away from the same and to be supported thereby at an angle to said vertical plane of the blade while the holder is supported on said cutting edge portion, a rigid element pivoted on said free end of said member to extend inwardly in reverse direction toward said holder, and abrasive means on the inner end of said element including an abrasive surface presented inwardly, the blade thereby adapted to be sharpened by sliding said holder longitudinally of the blade frictionally to engage said abrasive surface inwardly against the beveled face of the blade.

2. A device as set forth in claim 1, wherein resilient means is provided for yieldingly pivotally urging said element toward said member whereby said abrasive surface will yieldingly frictionally engage said beveled surface.

3. A device as set forth in claim 2, wherein said member is pivoted on said holder, and wherein is included a part relatively fixed on said holder and manually operable means between said fixed part and said member for varying the fixed angle at which said member extends from the pivotal axis thereof outwardly of said holder.

4. A device as set forth in claim 3, said part being an arm adjustably pivoted on said holder on the same axis as said member, and means being provided for releasably locking said arm against pivotal movement on the holder.

References Cited in the file of this patent FOREIGN PATENTS 606,000 Germany Nov. 23, 1934- 

